Teletypewriter system



May 30, 1944 D. B. PERRY 2,350,186

TELETYPEWRITER SYSTEM Filed June 27, 1941 2 Sheets-5h66?.A 1 n.+ Ilm-ilu G IMI-hr,

#s @www gi i I 4* N! LIIIIIHI Ho Ilm-n. lNvENToR ATTORNEY May 30, 1944.

D. B. PERRY TELETYPEWRI TER SYSTEM 2 Shees-Sheet 2 Filed June 27, 1941 mix@ INVENToR BY 5.591045/ 0( ATTORNEY Patented May 30, 1944 TELETYPEWRITER SYSTEM Donald Burke Perry, Maplewood, N. J., assignor to American Telephone and Telegraph Company, a corporation of New York Application June 27, 1941, Serial No. 399,981

3 Claims.

This invention relates to teletypewriter systems, and more particularly to arrangements for p interconnecting a central teletypewrter station with a plurality of outlying teletypewriter stations so that one or more of the outlying stations may transmit intelligence to or receive intelligence from the central station.

It is one of the objects of this invention to provide a teletypewriter system including a central station and a plurality of outlying stations so that intelligence may be communicated from the central station to one or more of the outlying stations over radial circuits at the same time.

It is another object of this invention to provide a teletypewriter system including a central station having, for example, two teletypewriter sets, and a plurality of outlying stations each having an individual teletypewriter set, the system being so arranged that one of the sets at the central station may be connected to one or more of the outlying teletypewriter sets, and the other set at the central station connected to another one or more of the other outlying remaining teletypewriter sets at the same time.

It is another object of this invention to pro? Vide a teletypewriter system having a central station at which may be located attended teletypewriter sets and an unattended teletypewriter set so that one or more teletypewriter sets at outlying points may be connected automatically over radial loop circuits to the central station for simultaneously transmitting intelligence to the central station to operate either the attended or the unattended sets at the central station.

The arrangement of this invention comprises a radial teletypewriter network with a number of outlying teletypewriter points and a fewer number of teletypewriters at the central point. According to one aspect of the invention, calls originating at outlying points may be automatically picked up at a receiving-only teletypewriter which may be unattended at the central point. According to another aspect of this invention, a call originating at the central point may be made manually by operating a key at the central point which automatically starts the motor at the outlying point or points. Theoutlying station or stations may be attended or unattended when the call is received from the central station.

These and other objects of this invention will be apparent from the following description of the invention when considered'in connection with the accompanying drawings in which Figure 1 shows one embodiment of the invention merely forthe purpose of illustration, and Fig. 2 illus.-

trates a modification of part of the circuit of Fig. 1 to accommodate a plurality of receivingonly teletypewriter sets.

Referring to Fig. 1 `of the drawings, there are shown two teletypewriter sets designated TTYi and TTYz anda third teletypewriter set TIYa, al1 of which may be located at a central station. There may be attendants at the central stationto control the operation of the teletypewriter sets TTYi and TTYz, but the teletypewriter set TTY: is an unattended set capable only of receiving messages. known in the art as teletypewriters Nos. 14, 15, 19 or 26. The set TTYa may be of any Wellknown type, as teletypewriters Nos. 14, 15 or 26. The central station is vconnected to a plurality of outlying stations .each of which is supplied with an individual teletypewriter set, the set T'IY 11 at station No. 1 being connected to the central station by a loop circuit P1, the set .T'I'Yiz at station No. 2 being connected to the central station by a loop circuit P2, and still other stations, such, for

example, as station No. N having a set TTYn.

connected to the central oflice by a loop circuit Pn. The outlying teletypewriter sets TTYn, TTYiz TTY may also be of a type such as Nos. 14, l5', 19 or 26page or tape teletypewriters of wellknown construction.

At the central oce there are keys K1 and K'i associated with the outlying station No. 1, keys K2 and Kz 'associated with the outlying station No. 2, and `keys Kn and Kfm associated With the station No. N. The key K0 is commonto all of the central oiilce apparatus and may be used, for example, for connecting either one of the teletypewriter 'sets TTYi and 'I'IYz to 'broadcast to two or more of the outlying teletypewriter sets TTYii, TTY12 TTYn. There are two lamps Li `and L2 at the central cnice common to each outlying station, the lamp vL1 being used to indicate a busycondition at the set TI'Yu atstation No. 1, and the lamp L2 that a `call is waiting, as will beexplained hereinafter. Likewise the lamps L3 and Lrare used for similar purposes in regardv to another vof the outlying teletypewriters, such asstation No. 2 will then operate his break keyy BK2 momentarily. This will cause the central oiiice relay A2, which is associatedwithstation No.. 2, tobe released. It will be observed that themain 'winding of relay Aa, Awhich is at `its rightand connected. toa positive-battery, extends to The sets TTYi and TTYz may be thosev back contact, the winding of relay H and ground.

The illumination of lamp L4 will indicate at the central station that a call from the outlying station No. 2 is Waiting or is automatically being picked up.

The release of relay A2 is operation of the stepping magnet SM, the winding of which is connected at one side to a posia'ccompanied by the l tive battery, and at Vthe other side through its armature and back contact and the arm of selector S1 and its contact O` to the grounded armature at the extreme right of relay A2 Tand..

its back contact. The stepping magnet SM'simultaneously actuates all of the selectorV arms S1, S2, Syand S4. With the energization of the stepping magnet SM its own vcircuit isopened and as it releases the armsv of the various selectors will `advance one step to point'. l. On'freaching point 1 the stepping magnet SM will Abe re-energized, current flowing from .its associated battery through the Windingof -the stepping magnet SM and over a circuit which includes its armature and back contact, theV arm of selector S1 and its contact 1, the lowermost armature of relay B1 and its back contact and the grounded' armaturev at the extreme right. of relay A1 and` its make contact. This will cause the stepping magnetSM to break its own circuit and cause the selector to step and to advance the arms of the selectors S1 to S4 another step to point 2. Here the .stepping magnet SM lwill nd, its circuit open at the make contactof the armature at the extreme right of relayvA2, the interconnectedfcircuit including the selector arm S1 andits contact 2, the lowermost armature and back contact of relay B2 and the make contact of the armature at the extreme right ofrelay A2, which is open because of the prior release of relay A2. Tliusit will be seen that the selector arm S1 will advance until it reaches a contact such as point/2 corresponding to one of the A relays, y

such as. relay A2, which has been released by the break signal from the corresponding station No. 2.

The closure of contact 2 by the' arm of thel selector S3 will cause relays G, B2 and H to operate, the interconnected circuit including the winding of relay G,'the arm of selector S3 and its c ontact No. 2, the winding of relay B2, the inner left armature of relay A2 and its back contact, the winding of relay H and ground. The

operation of relay B2 will complete a second or' locking circuit forV this relay, the locking circuit including the inner upper armature and make contact of relay B2 and the armature and back contact of relay C2. The operation of relayB2 Will also cause relay. D2 to become operated, the circuit including the battery connected to the Winding of relay D2, the uppermost arma-- turelof Vrelay B2 and its grounded.

The receiving magnetA RMof the unattended teletypewriter set ,'IIYs will be. closed through selector S2 by completion of acircuit which inmake contact which is cludes the positiveb'attery connected to one side 75 of receiving magnet and the receiving magnet itself; the inner armature and make con-l tact of relay G, the Winding of relay L, the arm of selector S2 and its contact No. 2, the lower inner armature of relay B2 and its make contact and the line circuit to the outlying teletypewriter set TTY12, which includes contacts 201 and 202 of key K2,` contacts 203, 204, 205 and 206 of key K2 and the loop circuit P2. The completion of this circuit to station No. 2 will start the motor (not shown) of the teletypewriter TTY12, which is of the start-after-break" type'of well-known construction. Thus after a break signal is received from station No. 2 the receiving magnet RM of the teletypewriter T'I'Ya will be connected over the loop circuit P2 to the teletypewriter TTY12, starting the motor at the latter set and, therefore, permitting the attendant at station No. 2 to send to the cenral station in a well-known manner.

Upcn the operation of relay D2 the relay A2 will then become re-operated, the circuit for operating relay A2 including the positive battery connected to its windings, the secondary (or left) winding of relay A2 and the armature and make contact of relay D2. The re-operation of relay A2 will cause the lamp L4 to become extinguished by opening its circuit extending to the back contact of the armature at the extreme left of relay A2. At the same time the busy lamp L2 will be lit. The circuit for lamp L3 includes the battery connected to its left-hand terminal, the middle upper armature and make contact of relay B2, the armature at the extreme left of relay A2 and its make contact, the winding of relay H and ground. The busy lamp L2 will indicate at the central station that the teletypewriter TTY12 at station No. 2 is sending to the central station.

At the end of the transmission from station No. 2 to the central station the operator at station No. 2 may send a character such as Figs H, which will be employed to close the contact Y of the teletypewriter T'I'Ys at the central station in a manner well understood 'by those skilled in the art. The transmission of the character Figs H will at the same time stop the motor at station No. 2 in accordance with well-established practice.

The operation of relay C2 will cause relay B2 to., release by opening the circuit in series with the; winding of relay B2I which includes the upper inner armature and make contact 0f relay B2; and the armature of relay C2, which is disconnected from its grounded back contact. 'Ihe release of relay B2 will substitute the main winding of relay A2 for the receiving magnet RM of teletypewriter TTYa in the line circuit of station 2. Thus the battery connected to the main winding of relay A2 sends current over a circuit which includes the right inner armature and make contact of relay A2, the break-after-make contact of relay B2, and the line circuit of station No. 2 which includes contacts 20| and 202 of key K'z,

contacts 203, 204, 205 and 2060i" key K2, 'and the magnetSM including 'the arm of selector S1Y and The closure of contact Y of setI 'I'IYs will cause relay C2 to become operated through selector S4, the interconnected circuit,l including the armature and contact Y of set. TTYs, the selector arm S4 and its contact No. 2 the Winding of relay C2 and its positive battery.,

its `contact 2, the lowermost armature of relay B2 and its back contact, the grounded armature at the extreme right of relay A2 and its make contact. Due to the operation of other A relays, such as relay An, in their normal conditions the stepping magnet SM will act to step arms S1-S4 of the selector around in a well-known manner and come to rest at their zero terminals. Thereafter the relay D2, which is of the slow-release type, will release. The release of relay D2 will then open the locking circuit of the secondary winding of relay A2, but relay A2 will remain operated. The circuit at the central station will then return to its normal condition, as indicated in the drawings, and both lamps L3 and L4 at the central station, which correspond to station No. 2, will be ready for subsequent operations. Any other outlying station that was ready to transmit to the central oii'ice set TTYa will then be connected to set TI'Ys, and so on.

For outgoing calls originating at but one of the teletypewriter sets, such as TTY1 of the central station, to an outlying station, such as station No. 2, the key K2 corresponding to station No. 2 may be moved upwardly. When this happens the teletypewriter set T'I'Y1, which is connected to a positive battery at its left, will be connected over contacts lill and |02 of key K1, and contacts 201 and 208 of key K2 to the loop circuit P2 which terminates in the teletypewriter set TTY12. The operation of key K2 also connects ground to the secondary winding of relay A2 to hold relay A2 operated as long as key K2 remains operated, the holding circuit including the grounded contact 208 and Contact 209 of key K2, the secondary winding of relay A2 and its positive battery. The attendant at teletypewriter TTY1 may operate his break key (not shown), and thereby start the motor for the teletypewriter set TTY1 as well as the motor at station No. 2, which controls the operation of the teletypewriter set TTY12. At the end of the message the operator at the central oflce may send a character, such as Figs H, to stop both the motor of teletypewriter TI'Y12 at station No. 2 and that of teletypewriter TTY1.

Suppose it is desired to transmit from one teletypewriter at the central station, such as TTY1, simultaneously to two or more outlying stations, such as stations Nos. 1 and 2. In that case keys K1 and Kz are operated. The operation of key K1 will connect the teletypewriter TTY11 at station No. 1 to the armature of relay E1 over a circuit which includes loop P1, contacts |05 and |05 of key K1, contacts |01 and |08 of key K1, contacts and ||2 of key K1 to the armature of relay E1, the contact M of which is connected to battery. The teletypewriter TTY12 is likewise connected to the armature of relay E2 over a circuit which includes loop P2, contacts 206, 205, 204 and 203 of key K2, contacts 202 and 2|2 of key K2 to the armature of relay E2, the marking contact M of which is connected to battery. The key K0 is maintained in its normal position as shown. The signals or message transmitted from teletypewriter T'IY1 will be relayed to relay F, the interconnected circuit including contacts |0| and |02 of key K1, 201 and 2|3 of key IQ, 50| and 502 of key Kn, contacts 5| and 50 of key Ko, and the winding of relay F, which is grounded at its right-hand terminal. 'I'he signals traversing the winding of relay F will be repeated in.

the windings of relays E1 and E2, which are in series and connected to the contacts M and S of relay F and its armature. When contact M is closed by the armature of relay F by amark'- ing pulse from set T'I'Y1, current will flow from the battery associated with relay F, through resistor 6| and over the series circuit of the windings of relays Ei, E2 and En to ground. When contact S is closed by the armature of relay F, the same battery will send current through resistor 62 and through the series windings of relays E1, E2 and En, but this current is in the reverse direction.

Thus it will be observed that by vibrating the armature of relay F between its two contacts M and S in accordance With signals, there will be a reversal of current through the windings of the various E relays. Inasmuch as the armature of relay E1, for example, is connected to the teletypewriter 'ITlY11, the signals traversing the Winding of relay E1 will be repeated in the teletypewriter receiving magnet RC1 of teletypewriter TTY11. Likewise the signals traversing the winding of relay E2 will be repeated in the receiving magnet RC2 of teletypewriter T'IY12. The signals sent from teletypewriter 'IIYi correspondingly actuate the armature of relay F. This in turn will actuate the armatures of relays E1 and E2 in accordance with the same signals, and the armatures of relays E1 and E2 simultaneously transmit the same signals to the receiving magnets RC1 and RC2, respectively, at the outlying stations Nos. 1 and 2 over radial loop circuits P1 and P2.

It has been pointed out thatwhen a message is to be transmitted from the teletypewriter T'I'Y1 at the central station to one or more outlying teletypewriters simultaneously, the key K0 is unoperated. Should it be desired to send a message from the other teletypewriter TTYz at the central station, the key K0 will then be operated so that its contact arm 50 closes contact 52. The relay F will then receive the message from the teletypewriter TTYz, actuate its armature in accordance with the signals emanating from the teletypewriter TTYz and transmit the signals to the desired outlying station or stations.

The relay H may be employed to control an alarm circuit including the lamp L10, which is connected to the inner make contact of relay H. Relay H may also be employed to operate a buzzer circuit including a buzzer BZ and a key K10 connected to the outer make contact of relay H. Moreover, the relay L may be employed to control a pilot alarm circuit PA, which is connected to the back contact of the armature of relay L. '.Ihe relay Lis preferably ofthe slow-release type, 1n which case the pilot alarm circuit will be operated only when the relay L has been fully released.

The arrangements shown in the drawing may be used for interconnecting a central station with a plurality of radially arranged outlying stations, such as stations Nos. l, 2 N, so that two- Way service may at times be provided between the central station and one or more of the various outlying stations. The central station is set up so that amessage may be transmitted from any one of the outlyingr stations to the central station even when the central station is unattended. A circuit of the type here shown and described may be used for interconnecting various business oices to a central ofiice, or if desired, a plurality of outlying districts where air raid or other information regarding the national defense may be received and conveyed to the central station where the information so received may be recorded and promptly plotted. One ofthe outstanding features vof this invention is that it provides for the interconnection of outlying stations each of which has its individual teletypewriter set with a central station, which may be attended or unattended, and the central station includes a smaller number of teletypewriter sets than are in the various outlying districts.

While the drawing illustrates a plurality of batteries the negative terminals of which are all grounded, it Will be understood that all of these batteries may be one and the same battery.

It will also be understood that with this disclosure before him one skilled in the art may connect more than two attended teletypewriter sets at the central station. The circuit modications for the additional teletypewriter sets, however, need not be shown. Moreover, the circuit may also be modified to include two or more unattended teletypewriter sets used exclusively for receiving, each of which would be similar to the one designated TTYa. This modication of Fig. 1 is shown in Fig. 2.

Fig. 2 shows a circuit which may be substituted for a part of the arrangement of Fig. 1 to provide three (or more) teletypewriters TTY31, T'IYsz and T'IYas each of which is capable oi receiving messages only. Each teletypewriter such as TTY31 has associated with it a selector having four arms as, for example, S11, S21, S31 and S41 and three relays as, for example, L1, G1 and X1 and a stepping magnet such as SM1.

It may be stated in general that if one of the outlying teletypewriters as, for example, TIfYu of Fig. 1 initiates a call, the teletypewriter TT'Yai will be connected to the outlying set TTY11 for communication. If while communication is taking place, another outlying set, as, for example, TTY12 initiates a call, the next teletypewriter TTYaz will be connected to the second set T'IYiz for communication. A similar connection may be made to set TTYas from another outlying teletypewriter such as T'IYn.

If while communication is taking place between teletypewriters TTY12 and TTY32 a call from another set such as TTY arrives after the set TTYai has completed receiving a message, the call from set TTYn will be taken byset T'I'Ya1. In other Words, the receiving-,only sets will be operated in order, that is, rst 'TTYs1, next TTYaz, then TTYaa, etc., except in the event that one of the lower-numbered sets such as T'IYai has previously completed receiving a `message. In the latter case the previously operated lowestnumbered idle set TTYai will pick up the message' rather than one of the higher-numbered idle sets.

Let it be assumed that sets TTY 11 and TTYaz are interconnected on a call from TTY11. Relays L2 and G2 will be operated in the same manner as previously described foi-the operation of relays L and G of Fig. l. The operation of relay Gn will cause relay X2 to operate upon the closure of the make Contact at the right of relay G2. 1 f

Let it be further assumed that While the connection to set TIYc'z remains continuous, the Set TTYai has comp-letedreceiving its call' and is idle While another call from, for example, set T'I'Yn arrives. Relay An then releases with the arrival of the break signal from set T'IYil. The ground at the armature at the extreme right of relay An Will be connected to point e1 of Fig. 2 and since relay X1 is released, its armature will pass the grounded circuit i-through contact O and the arm of selector S11'and through the armature at the extremeleft of relay G1, to the stepping magnet SM1. Upon the operation of stepping magnet SM1, the circuit to its winding will be broken and thereby advance the selector arms S11, S21, S31 and S41 one step to point 1. The stepping magnet will then be re-operated and stepped again and again until the arms S11S41 reach their terminals marked N.

When terminals N are reached, relays G1 and Bn (of Fig. 1) operate, the circuit including the winding of relay G1, contact N and selector arm S31, conductor h3, winding of relay B11 of Fig. 1, the inner left armature and back contact of relay An, the winding of relay H and ground. Re-

lay G1 operates to close the communication circuit extending between sets TTY31 and TTY, the interconnected circuit including, among other things, the inner left armature and make contact of relay `G1, the winding of relay L1, contact N and the arm of selector S21 to conductor h2. The operation of relay G1 also causes relay X1 to operate. The relay X1 is of the slow operate type, allowing time for relay B1 to operate relay D1 which in turn will re-operate relay A1 before the completion of the operation of relay X1. The full operation of relay X1 connects conductor e1 to the armature of relay X3 over a circuit which includes the armature and front contact of relay X1 and the armature and front contact of relay X2. Thus the circuit arrangement is prepared so that the immediately succeeding call from any of the other outlying sets may be picked up by set TTYaa.

While this invention has been shown and described in certain particular arrangements merely for the purpose of illustration, it will be understood that the general principles of this invention may be applied to other and widely varied organizations without departing from the spirit of the invention and the scope of the appended claims.

What is claimed is:

l. In a teletypewriter system. the combination of a central station which may be unattended, an unattended teletypewriter set at the central station. a plurality of outlying stations at each of which there is a teletypewriter set, a step-bystep selector at the central station, means responsive to a break signal received from any one of the teletypewriters at the various outlying stations to operate the selector to connect the central station teletypewriter set only to the teletypewriter set at the outlying station from which the break signal is received. means responsive to a predetermined signal from the set at the outlying station designating the termination of the message from the set at the outlying station to further operate the selector to immediately return the selector to its unoperated position and at the same time disconnect the set at the outlying station from the set at the central station,l means including apparatus at the central station responsive to a break signal received from a second teletypewriter set at a diiTerent outlying station to preparethe circuit to connect the latter teletypewriter set to the central station teletypewriter set, and means responsive to the disconnection of the first-mentioned outlying teletypewritei` set from the central station teletypewriter set to connect the second teletypewriter setto the central station teletypewriter set.

2. In a teletypewriter system, the combination of a centrally located unattended teletypewriter set capable only of receiving messages, a plurality of teletypewriter sets at outlying points with respect to the central teletypewriter, a step-bystep selector associated with the central teletypewriter and having a plurality of terminals each of which corresponds to but one of the outlying 'teletypewritera means responsive to a break signal received from any one of the outlying teletypewriters to operate said selector step-by-step to connect the central teletypewriter to the outlying teletypewriter from which the break signal is received to the exclusion of all other teletype- Writers, means responsive to a predetermined signal designating the termination of the message from the outlying teletypewriter to further operate the selector and immediately return it to its unoperated position, and means responsive to the disconnection of said outlying teletype- Writer from said central teletypewriter for automatically connecting to the central teletypewriter any other outlying teletypewriter awaiting connection to the central teletypewriter.

3. In a teletypewriter system, the combination of a central teletypewriter capable of receiving messages only, a plurality of outlying teletypewriters which may be connected to the central teletypewriter over radial circuits, a stepby-step selector associated With the central teletypewriter, means responsive to break signals from the various outlying teletypewriters to prepare the circuits connecting said outlying teletypewriters to the central teletypewriter, only the first outlying teletypewriter being operatively connected to the central teletypewriter by the selector, and means responsive to the disconnection of an outlying teletypewriter from the central teletypewriter for progressively connecting each of the remaining outlying teletypewriters in order to the central teletypewriter.

DONALD B. PERRY. 

